Method and apparatus for video coding

ABSTRACT

Aspects of the disclosure provide method and apparatus for video coding. In some examples, an apparatus includes processing circuitry for video decoding. In the method, a combined inter coding unit mode indicator is received. Inter-prediction information for one of a plurality of blocks in a current picture is received and the inter-prediction information includes motion information of the one of the plurality of blocks. Each of the plurality of blocks is reconstructed according to the inter-prediction information of the one of the plurality of blocks based on a determination that the combined inter coding unit indicator indicates that each of the plurality of blocks partitioned from a parent block is associated with the inter-prediction information of the one of the plurality of blocks.

INCORPORATION BY REFERENCE

This present disclosure claims the benefit of priority to U.S.Provisional Application No. 62/696,525, “COMBINED INTER CU IN FLEXIBLETREE STRUCTURE” filed on Jul. 11, 2018, which is incorporated byreference herein in its entirety.

TECHNICAL FIELD

The present disclosure describes embodiments generally related to videocoding.

BACKGROUND

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent the work is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentdisclosure.

Video coding and decoding can be performed using inter-pictureprediction with motion compensation. Uncompressed digital video caninclude a series of pictures, each picture having a spatial dimensionof, for example, 1920×1080 luminance samples and associated chrominancesamples. The series of pictures can have a fixed or variable picturerate (informally also known as frame rate), of, for example 60 picturesper second or 60 Hz. Uncompressed video has significant bitraterequirements. For example, 1080p60 4:2:0 video at 8 bit per sample(1920×1080 luminance sample resolution at 60 Hz frame rate) requiresclose to 1.5 Gbit/s bandwidth. An hour of such video requires more than600 GByte of storage space.

One purpose of video coding and decoding can be the reduction ofredundancy in the input video signal, through compression. Compressioncan help reduce aforementioned bandwidth or storage space requirements,in some cases by two orders of magnitude or more. Both lossless andlossy compression, as well as a combination thereof can be employed.Lossless compression refers to techniques where an exact copy of theoriginal signal can be reconstructed from the compressed originalsignal. When using lossy compression, the reconstructed signal may notbe identical to the original signal, but the distortion between theoriginal and reconstructed signal is small enough to make thereconstructed signal useful for the intended application. In the case ofvideo, lossy compression is widely employed. The amount of distortiontolerated depends on the application; for example, users of certainconsumer streaming applications may tolerate higher distortion thanusers of television contribution applications. The compression ratioachievable can reflect that: higher allowable/tolerable distortion canyield higher compression ratios.

In High Efficiency Video Coding (HEVC), a coding tree unit (CTU) issplit into coding units (CUs) by using a quadtree structure denoted ascoding tree to adapt to various local characteristics. The decisionwhether to code a picture area using inter-picture (temporal) orintra-picture (spatial) prediction is made at the CU level. Each CU canbe further split into one, two or four prediction units (PUs) accordingto the PU splitting type. Inside one PU, the same prediction process isapplied and the relevant information is transmitted to the decoder on aPU basis. After obtaining the residual block by applying the predictionprocess based on the PU splitting type, a CU can be partitioned intotransform units (TUs) according to another quadtree structure like thecoding tree for the CU. One of key feature of the HEVC structure is thatit has the multiple partition conceptions including CU, PU, and TU. InHEVC, a CU or a TU can only be square shape, while a PU may be square orrectangular shape for an inter-predicted block.

Motion compensation can be a lossy compression technique and can relateto techniques where a block of sample data from a previouslyreconstructed picture or part thereof (reference picture), after beingspatially shifted in a direction indicated by a motion vector (MVhenceforth), is used for the prediction of a newly reconstructed pictureor picture part. In some cases, the reference picture can be the same asthe picture currently under reconstruction. MVs can have two dimensionsX and Y, or three dimensions, the third being an indication of thereference picture in use (the latter, indirectly, can be a timedimension).

In some video compression techniques, an MV applicable to a certain areaof sample data can be predicted from other MVs, for example from thoserelated to another area of sample data spatially adjacent to the areaunder reconstruction, and preceding that MV in decoding order. Doing socan substantially reduce the amount of data required for coding the MV,thereby removing redundancy and increasing compression. MV predictioncan work effectively, for example, because when coding an input videosignal derived from a camera (known as natural video) there is astatistical likelihood that areas larger than the area to which a singleMV is applicable move in a similar direction and, therefore, can in somecases be predicted using a similar motion vector derived fromneighboring area's MVs. That results in the MV found for a given area tobe similar or the same as the MV predicted from the surrounding MVs, andthat in turn can be represented, after entropy coding, in a smallernumber of bits than what would be used if coding the MV directly. Insome cases, MV prediction can be an example of lossless compression of asignal (namely: the MVs) derived from the original signal (namely: thesample stream). In other cases, MV prediction itself can be lossy, forexample because of rounding errors when calculating a predictor fromseveral surrounding MVs.

Various MV prediction mechanisms are described in H.265/HEVC (ITU-T Rec.H.265, “High Efficiency Video Coding,” December 2016). Out of the manyMV prediction mechanisms that H.265 offers, described here is atechnique henceforth referred to as “spatial merge.”

Referring to FIG. 1, a current block (101) that includes samples thathave been found by the encoder during the motion search process to bepredictable from a previous block of the same size that has beenspatially shifted. Instead of coding that MV directly, the MV can bedirected from metadata associated with one or more reference pictures,for example from the most recent (in decoding order) reference picture,using the MV associated with either one of five surrounding samples,denoted A0, A1, and B0, B1, B2 ((102) through (106), respectively). InH.265, the MV prediction can use predictors from the same referencepicture that the neighboring block is using.

SUMMARY

Aspects of the disclosure provide methods and apparatuses for videodecoding. In some embodiments, an apparatus for video decoding includesprocessing circuitry.

In one embodiment of the present disclosure, there is provided a methodfor video decoding in a decoder. In the method, a combined inter codingunit mode indicator is received. Inter-prediction information for one ofa plurality of blocks in a current picture is received and theinter-prediction information includes motion information of the one ofthe plurality of blocks. Each of the plurality of blocks isreconstructed according to the inter-prediction information of the oneof the plurality of blocks based on a determination that the combinedinter coding unit indicator indicates that each of the plurality ofblocks partitioned from a parent block is associated with theinter-prediction information of the one of the plurality of blocks.

In another embodiment of the present disclosure, there is provided anapparatus. The apparatus includes processing circuitry. The processingcircuitry receives a combined inter coding unit mode indicator. Theprocessing circuitry receives inter-prediction information for one of aplurality of blocks in a current picture. The inter-predictioninformation includes motion information of the one of the plurality ofblocks. The processing circuitry further reconstructs each of theplurality of blocks according to the inter-prediction information of theone of the plurality of blocks based on a determination that thecombined inter coding unit indicator indicates that each of theplurality of blocks partitioned from a parent block is associated withthe inter-prediction information of the one of the plurality of blocks.

Aspects of the disclosure also provide a non-transitorycomputer-readable medium storing instructions which when executed by acomputer for video decoding cause the computer to perform the method forvideo coding. In the method, a combined inter coding unit mode indicatoris received. Inter-prediction information for one of a plurality ofblocks in a current picture is received and the inter-predictioninformation includes motion information of the one of the plurality ofblocks. Each of the plurality of blocks is reconstructed according tothe inter-prediction information of the one of the plurality of blocksbased on a determination that the combined inter coding unit indicatorindicates that each of the plurality of blocks partitioned from a parentblock is associated with the inter-prediction information of the one ofthe plurality of blocks.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features, the nature, and various advantages of the disclosedsubject matter will be more apparent from the following detaileddescription and the accompanying drawings in which:

FIG. 1 is a schematic illustration of a current block and itssurrounding spatial merge candidates in accordance with H.265.

FIG. 2 is a schematic illustration of a simplified block diagram of acommunication system (200) in accordance with an embodiment.

FIG. 3 is a schematic illustration of a simplified block diagram of acommunication system (300) in accordance with an embodiment.

FIG. 4 is a schematic illustration of a simplified block diagram of adecoder in accordance with an embodiment.

FIG. 5 is a schematic illustration of a simplified block diagram of anencoder in accordance with an embodiment.

FIG. 6 shows a block diagram of an encoder in accordance with anotherembodiment.

FIG. 7 shows a block diagram of a decoder in accordance with anotherembodiment.

FIG. 8 shows a QTBT structure of block partitioning in accordance withan embodiment.

FIG. 9 is an exemplary schematic illustration of combining child codingunits in accordance with an embodiment.

FIG. 10 shows a flow chart outlining an exemplary process (1000)according to some embodiments of the disclosure.

FIG. 11 is a schematic illustration of a computer system in accordancewith an embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 2 illustrates a simplified block diagram of a communication system(200) according to an embodiment of the present disclosure. Thecommunication system (200) includes a plurality of terminal devices thatcan communicate with each other, via, for example, a network (250). Forexample, the communication system (200) includes a first pair ofterminal devices (210) and (220) interconnected via the network (250).In the FIG. 2 example, the first pair of terminal devices (210) and(220) performs unidirectional transmission of data. For example, theterminal device (210) may code video data (e.g., a stream of videopictures that are captured by the terminal device (210)) fortransmission to the other terminal device (220) via the network (250).The encoded video data can be transmitted in the form of one or morecoded video bitstreams. The terminal device (220) may receive the codedvideo data from the network (250), decode the coded video data torecover the video pictures and display video pictures according to therecovered video data. Unidirectional data transmission may be common inmedia serving applications and the like.

In another example, the communication system (200) includes a secondpair of terminal devices (230) and (240) that performs bidirectionaltransmission of coded video data that may occur, for example, duringvideoconferencing. For bidirectional transmission of data, in anexample, each terminal device of the terminal devices (230) and (240)may code video data (e.g., a stream of video pictures that are capturedby the terminal device) for transmission to the other terminal device ofthe terminal devices (230) and (240) via the network (250). Eachterminal device of the terminal devices (230) and (240) also may receivethe coded video data transmitted by the other terminal device of theterminal devices (230) and (240), and may decode the coded video data torecover the video pictures and may display video pictures at anaccessible display device according to the recovered video data.

In the FIG. 2 example, the terminal devices (210), (220), (230) and(240) may be illustrated as servers, personal computers and smart phonesbut the principles of the present disclosure may be not so limited.Embodiments of the present disclosure find application with laptopcomputers, tablet computers, media players and/or dedicated videoconferencing equipment. The network (250) represents any number ofnetworks that convey coded video data among the terminal devices (210),(220), (230) and (240), including for example wireline (wired) and/orwireless communication networks. The communication network (250) mayexchange data in circuit-switched and/or packet-switched channels.Representative networks include telecommunications networks, local areanetworks, wide area networks and/or the Internet. For the purposes ofthe present discussion, the architecture and topology of the network(250) may be immaterial to the operation of the present disclosureunless explained herein below.

FIG. 3 illustrates, as an example for an application for the disclosedsubject matter, the placement of a video encoder and a video decoder ina streaming environment. The disclosed subject matter can be equallyapplicable to other video enabled applications, including, for example,video conferencing, digital TV, storing of compressed video on digitalmedia including CD, DVD, memory stick and the like, and so on.

A streaming system may include a capture subsystem (313), that caninclude a video source (301), for example a digital camera, creating forexample a stream of video pictures (302) that are uncompressed. In anexample, the stream of video pictures (302) includes samples that aretaken by the digital camera. The stream of video pictures (302),depicted as a bold line to emphasize a high data volume when compared toencoded video data (304) (or coded video bitstreams), can be processedby an electronic device (320) that includes a video encoder (303)coupled to the video source (301). The video encoder (303) can includehardware, software, or a combination thereof to enable or implementaspects of the disclosed subject matter as described in more detailbelow. The encoded video data (304) (or encoded video bitstream (304)),depicted as a thin line to emphasize the lower data volume when comparedto the stream of video pictures (302), can be stored on a streamingserver (305) for future use. One or more streaming client subsystems,such as client subsystems (306) and (308) in FIG. 3 can access thestreaming server (305) to retrieve copies (307) and (309) of the encodedvideo data (304). A client subsystem (306) can include a video decoder(310), for example, in an electronic device (330). The video decoder(310) decodes the incoming copy (307) of the encoded video data andcreates an outgoing stream of video pictures (311) that can be renderedon a display (312) (e.g., display screen) or other rendering device (notdepicted). In some streaming systems, the encoded video data (304),(307), and (309) (e.g., video bitstreams) can be encoded according tocertain video coding/compression standards. Examples of those standardsinclude ITU-T Recommendation H.265. In an example, a video codingstandard under development is informally known as Versatile Video Codingor VVC. The disclosed subject matter may be used in the context of VVC.

It is noted that the electronic devices (320) and (330) can includeother components (not shown). For example, the electronic device (320)can include a video decoder (not shown) and the electronic device (330)can include a video encoder (not shown) as well.

FIG. 4 shows a block diagram of a video decoder (410) according to anembodiment of the present disclosure. The video decoder (410) can beincluded in an electronic device (430). The electronic device (430) caninclude a receiver (431) (e.g., receiving circuitry). The video decoder(410) can be used in the place of the video decoder (310) in the FIG. 3example.

The receiver (431) may receive one or more coded video sequences to bedecoded by the video decoder (410); in the same or another embodiment,one coded video sequence at a time, where the decoding of each codedvideo sequence is independent from other coded video sequences. Thecoded video sequence may be received from a channel (401), which may bea hardware/software link to a storage device which stores the encodedvideo data. The receiver (431) may receive the encoded video data withother data, for example, coded audio data and/or ancillary data streams,that may be forwarded to their respective using entities (not depicted).The receiver (431) may separate the coded video sequence from the otherdata. To combat network jitter, a buffer memory (415) may be coupled inbetween the receiver (431) and an entropy decoder/parser (420) (“parser(420)” henceforth). In certain applications, the buffer memory (415) ispart of the video decoder (410). In others, it can be outside of thevideo decoder (410) (not depicted). In still others, there can be abuffer memory (not depicted) outside of the video decoder (410), forexample to combat network jitter, and in addition another buffer memory(415) inside the video decoder (410), for example to handle playouttiming. When the receiver (431) is receiving data from a store/forwarddevice of sufficient bandwidth and controllability, or from anisosynchronous network, the buffer memory (415) may not be needed, orcan be small. For use on best effort packet networks such as theInternet, the buffer memory (415) may be required, can be comparativelylarge and can be advantageously of adaptive size, and may at leastpartially be implemented in an operating system or similar elements (notdepicted) outside of the video decoder (410).

The video decoder (410) may include the parser (420) to reconstructsymbols (421) from the coded video sequence. Categories of those symbolsinclude information used to manage operation of the video decoder (410),and potentially information to control a rendering device such as arender device (412) (e.g., a display screen) that is not an integralpart of the electronic device (430) but can be coupled to the electronicdevice (430), as is shown in FIG. 4. The control information for therendering device(s) may be in the form of Supplementary EnhancementInformation (SEI messages) or Video Usability Information (VUI)parameter set fragments (not depicted). The parser (420) mayparse/entropy-decode the coded video sequence that is received. Thecoding of the coded video sequence can be in accordance with a videocoding technology or standard, and can follow various principles,including variable length coding, Huffman coding, arithmetic coding withor without context sensitivity, and so forth. The parser (420) mayextract from the coded video sequence, a set of subgroup parameters forat least one of the subgroups of pixels in the video decoder, based uponat least one parameter corresponding to the group. Subgroups can includeGroups of Pictures (GOPs), pictures, tiles, slices, macroblocks, CodingUnits (CUs), blocks, Transform Units (TUs), Prediction Units (PUs) andso forth. The parser (420) may also extract from the coded videosequence information such as transform coefficients, quantized parametervalues, motion vectors, and so forth.

The parser (420) may perform entropy decoding/parsing operation on thevideo sequence received from the buffer memory (415), so as to createsymbols (421).

Reconstruction of the symbols (421) can involve multiple different unitsdepending on the type of the coded video picture or parts thereof (suchas: inter and intra picture, inter and intra block), and other factors.Which units are involved, and how, can be controlled by the subgroupcontrol information that was parsed from the coded video sequence by theparser (420). The flow of such subgroup control information between theparser (420) and the multiple units below is not depicted for clarity.

Beyond the functional blocks already mentioned, the video decoder (410)can be conceptually subdivided into a number of functional units asdescribed below. In a practical implementation operating undercommercial constraints, many of these units interact closely with eachother and can, at least partly, be integrated into each other. However,for the purpose of describing the disclosed subject matter, theconceptual subdivision into the functional units below is appropriate.

A first unit is the scaler/inverse transform unit (451). Thescaler/inverse transform unit (451) receives a quantized transformcoefficient as well as control information, including which transform touse, block size, quantization factor, quantization scaling matrices,etc. as symbol(s) (421) from the parser (420). The scaler/inversetransform unit (451) can output blocks comprising sample values, thatcan be input into aggregator (455).

In some cases, the output samples of the scaler/inverse transform (451)can pertain to an intra coded block; that is: a block that is not usingpredictive information from previously reconstructed pictures, but canuse predictive information from previously reconstructed parts of thecurrent picture. Such predictive information can be provided by an intrapicture prediction unit (452). In some cases, the intra pictureprediction unit (452) generates a block of the same size and shape ofthe block under reconstruction, using surrounding already reconstructedinformation fetched from the current picture buffer (458). The currentpicture buffer (458) buffers, for example, partly reconstructed currentpicture and/or fully reconstructed current picture. The aggregator(455), in some cases, adds, on a per sample basis, the predictioninformation the intra prediction unit (452) has generated to the outputsample information as provided by the scaler/inverse transform unit(451).

In other cases, the output samples of the scaler/inverse transform unit(451) can pertain to an inter-coded, and potentially motion compensatedblock. In such a case, a motion compensation prediction unit (453) canaccess reference picture memory (457) to fetch samples used forprediction. After motion compensating the fetched samples in accordancewith the symbols (421) pertaining to the block, these samples can beadded by the aggregator (455) to the output of the scaler/inversetransform unit (451) (in this case called the residual samples orresidual signal) so as to generate output sample information. Theaddresses within the reference picture memory (457) from where themotion compensation prediction unit (453) fetches prediction samples canbe controlled by motion vectors, available to the motion compensationprediction unit (453) in the form of symbols (421) that can have, forexample X, Y, and reference picture components. Motion compensation alsocan include interpolation of sample values as fetched from the referencepicture memory (457) when sub-sample exact motion vectors are in use,motion vector prediction mechanisms, and so forth.

The output samples of the aggregator (455) can be subject to variousloop filtering techniques in the loop filter unit (456). Videocompression technologies can include in-loop filter technologies thatare controlled by parameters included in the coded video sequence (alsoreferred to as coded video bitstream) and made available to the loopfilter unit (456) as symbols (421) from the parser (420), but can alsobe responsive to meta-information obtained during the decoding ofprevious (in decoding order) parts of the coded picture or coded videosequence, as well as responsive to previously reconstructed andloop-filtered sample values.

The output of the loop filter unit (456) can be a sample stream that canbe output to the render device (412) as well as stored in the referencepicture memory (457) for use in future inter-picture prediction.

Certain coded pictures, once fully reconstructed, can be used asreference pictures for future prediction. For example, once a codedpicture corresponding to a current picture is fully reconstructed andthe coded picture has been identified as a reference picture (by, forexample, the parser (420)), the current picture buffer (458) can becomea part of the reference picture memory (457), and a fresh currentpicture buffer can be reallocated before commencing the reconstructionof the following coded picture.

The video decoder (410) may perform decoding operations according to apredetermined video compression technology in a standard, such as ITU-TRec. H.265. The coded video sequence may conform to a syntax specifiedby the video compression technology or standard being used, in the sensethat the coded video sequence adheres to both the syntax of the videocompression technology or standard and the profiles as document in thevideo compression technology or standard. Specifically, a profile canselect a certain tools as the only tools available for use under thatprofile from all the tools available in the video compression technologyor standard. Also necessary for compliance can be that the complexity ofthe coded video sequence is within bounds as defined by the level of thevideo compression technology or standard. In some cases, levels restrictthe maximum picture size, maximum frame rate, maximum reconstructionsample rate (measured in, for example megasamples per second), maximumreference picture size, and so on. Limits set by levels can, in somecases, be further restricted through Hypothetical Reference Decoder(HRD) specifications and metadata for HRD buffer management signaled inthe coded video sequence.

In an embodiment, the receiver (431) may receive additional (redundant)data with the encoded video. The additional data may be included as partof the coded video sequence(s). The additional data may be used by thevideo decoder (410) to properly decode the data and/or to moreaccurately reconstruct the original video data. Additional data can bein the form of, for example, temporal, spatial, or signal noise ratio(SNR) enhancement layers, redundant slices, redundant pictures, forwarderror correction codes, and so on.

FIG. 5 shows a block diagram of a video encoder (503) according to anembodiment of the present disclosure. The video encoder (503) isincluded in an electronic device (520). The electronic device (520)includes a transmitter (540) (e.g., transmitting circuitry). The videoencoder (503) can be used in the place of the video encoder (303) in theFIG. 3 example.

The video encoder (503) may receive video samples from a video source(501)(that is not part of the electronic device (520) in the FIG. 5example) that may capture video image(s) to be coded by the videoencoder (503). In another example, the video source (501) is a part ofthe electronic device (520).

The video source (501) may provide the source video sequence to be codedby the video encoder (503) in the form of a digital video sample streamthat can be of any suitable bit depth (for example: 8 bit, 10 bit, 12bit, . . . ), any colorspace (for example, BT.601 Y CrCB, RGB, . . . )and any suitable sampling structure (for example Y CrCb 4:2:0, Y CrCb4:4:4). In a media serving system, the video source (501) may be astorage device storing previously prepared video. In a videoconferencingsystem, the video source (501) may be a camera that captures local imageinformation as a video sequence. Video data may be provided as aplurality of individual pictures that impart motion when viewed insequence. The pictures themselves may be organized as a spatial array ofpixels, wherein each pixel can comprise one or more samples depending onthe sampling structure, color space, etc. in use. A person skilled inthe art can readily understand the relationship between pixels andsamples. The description below focusses on samples.

According to an embodiment, the video encoder (503) may code andcompress the pictures of the source video sequence into a coded videosequence (543) in real time or under any other time constraints asrequired by the application. Enforcing appropriate coding speed is onefunction of a controller (550). In some embodiments, the controller(550) controls other functional units as described below and isfunctionally coupled to the other functional units. The coupling is notdepicted for clarity. Parameters set by the controller (550) can includerate control related parameters (picture skip, quantizer, lambda valueof rate-distortion optimization techniques, . . . ), picture size, groupof pictures (GOP) layout, maximum motion vector search range, and soforth. The controller (550) can be configured to have other suitablefunctions that pertain to the video encoder (503) optimized for acertain system design.

In some embodiments, the video encoder (503) is configured to operate ina coding loop. As an oversimplified description, in an example, thecoding loop can include a source coder (530) (e.g., responsible forcreating symbols, such as a symbol stream, based on an input picture tobe coded, and a reference picture(s)), and a (local) decoder (533)embedded in the video encoder (503). The decoder (533) reconstructs thesymbols to create the sample data in a similar manner as a (remote)decoder also would create (as any compression between symbols and codedvideo bitstream is lossless in the video compression technologiesconsidered in the disclosed subject matter). The reconstructed samplestream (sample data) is input to the reference picture memory (534). Asthe decoding of a symbol stream leads to bit-exact results independentof decoder location (local or remote), the content in the referencepicture memory (534) is also bit exact between the local encoder andremote encoder. In other words, the prediction part of an encoder “sees”as reference picture samples exactly the same sample values as a decoderwould “see” when using prediction during decoding. This fundamentalprinciple of reference picture synchronicity (and resulting drift, ifsynchronicity cannot be maintained, for example because of channelerrors) is used in some related arts as well.

The operation of the “local” decoder (533) can be the same as of a“remote” decoder, such as the video decoder (410), which has alreadybeen described in detail above in conjunction with FIG. 4. Brieflyreferring also to FIG. 4, however, as symbols are available andencoding/decoding of symbols to a coded video sequence by an entropycoder (545) and the parser (420) can be lossless, the entropy decodingparts of the video decoder (410), including the buffer memory (415), andparser (420) may not be fully implemented in the local decoder (533).

An observation that can be made at this point is that any decodertechnology except the parsing/entropy decoding that is present in adecoder also necessarily needs to be present, in substantially identicalfunctional form, in a corresponding encoder. For this reason, thedisclosed subject matter focuses on decoder operation. The descriptionof encoder technologies can be abbreviated as they are the inverse ofthe comprehensively described decoder technologies. Only in certainareas a more detail description is required and provided below.

During operation, in some examples, the source coder (530) may performmotion compensated predictive coding, which codes an input picturepredictively with reference to one or more previously-coded picture fromthe video sequence that were designated as “reference pictures”. In thismanner, the coding engine (532) codes differences between pixel blocksof an input picture and pixel blocks of reference picture(s) that may beselected as prediction reference(s) to the input picture.

The local video decoder (533) may decode coded video data of picturesthat may be designated as reference pictures, based on symbols createdby the source coder (530). Operations of the coding engine (532) mayadvantageously be lossy processes. When the coded video data may bedecoded at a video decoder (not shown in FIG. 5), the reconstructedvideo sequence typically may be a replica of the source video sequencewith some errors. The local video decoder (533) replicates decodingprocesses that may be performed by the video decoder on referencepictures and may cause reconstructed reference pictures to be stored inthe reference picture cache (534). In this manner, the video encoder(503) may store copies of reconstructed reference pictures locally thathave common content as the reconstructed reference pictures that will beobtained by a far-end video decoder (absent transmission errors).

The predictor (535) may perform prediction searches for the codingengine (532). That is, for a new picture to be coded, the predictor(535) may search the reference picture memory (534) for sample data (ascandidate reference pixel blocks) or certain metadata such as referencepicture motion vectors, block shapes, and so on, that may serve as anappropriate prediction reference for the new pictures. The predictor(535) may operate on a sample block-by-pixel block basis to findappropriate prediction references. In some cases, as determined bysearch results obtained by the predictor (535), an input picture mayhave prediction references drawn from multiple reference pictures storedin the reference picture memory (534).

The controller (550) may manage coding operations of the source coder(530), including, for example, setting of parameters and subgroupparameters used for encoding the video data.

Output of all aforementioned functional units may be subjected toentropy coding in the entropy coder (545). The entropy coder (545)translates the symbols as generated by the various functional units intoa coded video sequence, by lossless compressing the symbols according totechnologies known to a person skilled in the art as, for exampleHuffman coding, variable length coding, arithmetic coding, and so forth.

The transmitter (540) may buffer the coded video sequence(s) as createdby the entropy coder (545) to prepare for transmission via acommunication channel (560), which may be a hardware/software link to astorage device which would store the encoded video data. The transmitter(540) may merge coded video data from the video coder (503) with otherdata to be transmitted, for example, coded audio data and/or ancillarydata streams (sources not shown).

The controller (550) may manage operation of the video encoder (503).During coding, the controller (550) may assign to each coded picture acertain coded picture type, which may affect the coding techniques thatmay be applied to the respective picture. For example, pictures oftenmay be assigned as one of the following picture types:

An Intra Picture (I picture) may be one that may be coded and decodedwithout using any other picture in the sequence as a source ofprediction. Some video codecs allow for different types of Intrapictures, including, for example Independent Decoder Refresh (“IDR”)Pictures. A person skilled in the art is aware of those variants of Ipictures and their respective applications and features.

A Predictive picture (P picture) may be one that may be coded anddecoded using intra prediction or inter prediction using at most onemotion vector and reference index to predict the sample values of eachblock.

A Bi-directionally Predictive Picture (B Picture) may be one that may becoded and decoded using intra prediction or inter prediction using atmost two motion vectors and reference indices to predict the samplevalues of each block. Similarly, multiple-predictive pictures can usemore than two reference pictures and associated metadata for thereconstruction of a single block.

Source pictures commonly may be subdivided spatially into a plurality ofsample blocks (for example, blocks of 4×4, 8×8, 4×8, or 16×16 sampleseach) and coded on a block-by-block basis. Blocks may be codedpredictively with reference to other (already coded) blocks asdetermined by the coding assignment applied to the blocks' respectivepictures. For example, blocks of I pictures may be codednon-predictively or they may be coded predictively with reference toalready coded blocks of the same picture (spatial prediction or intraprediction). Pixel blocks of P pictures may be coded predictively, viaspatial prediction or via temporal prediction with reference to onepreviously coded reference pictures. Blocks of B pictures may be codedpredictively, via spatial prediction or via temporal prediction withreference to one or two previously coded reference pictures.

The video encoder (503) may perform coding operations according to apredetermined video coding technology or standard, such as ITU-T Rec.H.265. In its operation, the video encoder (503) may perform variouscompression operations, including predictive coding operations thatexploit temporal and spatial redundancies in the input video sequence.The coded video data, therefore, may conform to a syntax specified bythe video coding technology or standard being used.

In an embodiment, the transmitter (540) may transmit additional datawith the encoded video. The source coder (530) may include such data aspart of the coded video sequence. Additional data may comprisetemporal/spatial/SNR enhancement layers, other forms of redundant datasuch as redundant pictures and slices, Supplementary EnhancementInformation (SEI) messages, Visual Usability Information (VUI) parameterset fragments, and so on.

A video may be captured as a plurality of source pictures (videopictures) in a temporal sequence. Intra-picture prediction (oftenabbreviated to Intra prediction) makes uses of spatial correlation in agiven picture, and inter-picture prediction makes uses of the (temporalor other) correlation between the pictures. In an example, a specificpicture under encoding/decoding, which is referred to as a currentpicture, is partitioned into blocks. When a block in the current pictureis similar to a reference block in a previously coded and still bufferedreference picture in the video, the block in the current picture can becoded by a vector that is referred to as a motion vector. The motionvector points to the reference block in the reference picture, and canhave a third dimension identifying the reference picture, in casemultiple reference pictures are in use.

In some embodiments, a bi-prediction technique can be used in theinter-picture prediction. According to the bi-prediction technique, tworeference pictures, such as a first and a second reference picture thatare both prior in decoding order to the current picture in the video(but may be in the past and future, respectively, in display order) areused. A block in the current picture can be coded by a first motionvector that points to a first reference block in the first referencepicture, and a second motion vector that points to a second referenceblock in the second reference picture. The block can be predicted by acombination of the first reference block and the second reference block.

Further, a merge mode technique can be used in the inter-pictureprediction to improve coding efficiency.

According to some embodiments of the disclosure, predictions, such asinter-picture predictions and intra-picture predictions are performed inthe unit of blocks. For example, according to the HEVC standard, apicture in a sequence of video pictures is partitioned into coding treeunits (CTU) for compression, the CTUs in a picture have the same size,such as 64×64 pixels, 32×32 pixels, or 16×16 pixels. In general, a CTUincludes three coding tree blocks (CTBs), which are one luma CTB and twochroma CTBs. Each CTU can be recursively quadtree split into one ormultiple coding units (CUs). For example, a CTU of 64×64 pixels can besplit into one CU of 64×64 pixels, or 4 CUs of 32×32 pixels, or 16 CUsof 16×16 pixels. In an example, each CU is analyzed to determine aprediction type for the CU, such as an inter prediction type or an intraprediction type. The CU is split into one or more prediction units (PUs)depending on the temporal and/or spatial predictability. Generally, eachPU includes a luma prediction block (PB), and two chroma PBs. In anembodiment, a prediction operation in coding (encoding/decoding) isperformed in the unit of a prediction block. Using a luma predictionblock as an example of a prediction block, the prediction block includesa matrix of values (e.g., luma values) for pixels, such as 8×8 pixels,16×16 pixels, 8×16 pixels, 16×8 pixels and the like.

FIG. 6 shows a diagram of a video encoder (603) according to anotherembodiment of the disclosure. The video encoder (603) is configured toreceive a processing block (e.g., a prediction block) of sample valueswithin a current video picture in a sequence of video pictures, andencode the processing block into a coded picture that is part of a codedvideo sequence. In an example, the video encoder (603) is used in theplace of the video encoder (303) in the FIG. 3 example.

In an HEVC example, the video encoder (603) receives a matrix of samplevalues for a processing block, such as a prediction block of 8×8samples, and the like. The video encoder (603) determines whether theprocessing block is best coded using intra mode, inter mode, orbi-prediction mode using, for example, rate-distortion optimization.When the processing block is to be coded in intra mode, the videoencoder (603) may use an intra prediction technique to encode theprocessing block into the coded picture; and when the processing blockis to be coded in inter mode or bi-prediction mode, the video encoder(603) may use an inter prediction or bi-prediction technique,respectively, to encode the processing block into the coded picture. Incertain video coding technologies, merge mode can be an inter pictureprediction submode where the motion vector is derived from one or moremotion vector predictors without the benefit of a coded motion vectorcomponent outside the predictors. In certain other video codingtechnologies, a motion vector component applicable to the subject blockmay be present. In an example, the video encoder (603) includes othercomponents, such as a mode decision module (not shown) to determine themode of the processing blocks.

In the FIG. 6 example, the video encoder (603) includes the interencoder (630), an intra encoder (622), a residue calculator (623), aswitch (626), a residue encoder (624), a general controller (621) and anentropy encoder (625) coupled together as shown in FIG. 6.

The inter encoder (630) is configured to receive the samples of thecurrent block (e.g., a processing block), compare the block to one ormore reference blocks in reference pictures (e.g., blocks in previouspictures and later pictures), generate inter prediction information(e.g., description of redundant information according to inter encodingtechnique, motion vectors, merge mode information), and calculate interprediction results (e.g., predicted block) based on the inter predictioninformation using any suitable technique.

The intra encoder (622) is configured to receive the samples of thecurrent block (e.g., a processing block), in some cases compare theblock to blocks already coded in the same picture, generate quantizedcoefficients after transform and, in some cases also intra predictioninformation (e.g., an intra prediction direction information accordingto one or more intra encoding techniques).

The general controller (621) is configured to determine general controldata and control other components of the video encoder (603) based onthe general control data. In an example, the general controller (621)determines the mode of the block, and provides a control signal to theswitch (626) based on the mode. For example, when the mode is the intra,the general controller (621) controls the switch (626) to select theintra mode result for use by the residue calculator (623), and controlsthe entropy encoder (625) to select the intra prediction information andinclude the intra prediction information in the bitstream; and when themode is the inter mode, the general controller (621) controls the switch(626) to select the inter prediction result for use by the residuecalculator (623), and controls the entropy encoder (625) to select theinter prediction information and include the inter predictioninformation in the bitstream.

The residue calculator (623) is configured to calculate a difference(residue data) between the received block and prediction resultsselected from the intra encoder (622) or the inter encoder (630). Theresidue encoder (624) is configured to operate based on the residue datato encode the residue data to generate the transform coefficients. In anexample, the residue encoder (624) is configured to convert the residuedata from a spatial domain to a frequency domain, and generate thetransform coefficients. The transform coefficients are then subject toquantization processing to obtain quantized transform coefficients.

The entropy encoder (625) is configured to format the bitstream toinclude the encoded block. The entropy encoder (625) is configured toinclude various information according to a suitable standard, such asHEVC standard. In an example, the entropy encoder (625) is configured toinclude the general control data, the selected prediction information(e.g., intra prediction information or inter prediction information),the residue information, and other suitable information in thebitstream. Note that, according to the disclosed subject matter, whencoding a block in the merge submode of either inter mode orbi-prediction mode, there is no residue information.

FIG. 7 shows a diagram of a video decoder (710) according to anotherembodiment of the disclosure. The video decoder (710) is configured toreceive a coded pictures that are part of a coded video sequence, anddecode the coded picture to generate a reconstructed picture. In anexample, the video decoder (710) is used in the place of the videodecoder (310) in the FIG. 3 example.

In the FIG. 7 example, the video decoder (710) includes an entropydecoder (771), an inter decoder (780), a residue decoder (773), areconstruction module (774), and an intra decoder (772) coupled togetheras shown in FIG. 7.

The entropy decoder (771) can be configured to reconstruct, from thecoded picture, certain symbols that represent the syntax elements ofwhich the coded picture is made up. Such symbols can include, forexample, the mode in which a block is coded (such as, for example,intra, inter, b-predicted, the latter two in merge submode or anothersubmode), prediction information (such as, for example, intra predictioninformation or inter prediction information) that can identify certainsample or metadata that is used for prediction by the intra decoder(772) or the inter decoder (780) respectively residual information inthe form of, for example, quantized transform coefficients, and thelike. In an example, when the prediction mode is inter or bi-predictedmode, the inter prediction information is provided to the inter decoder(780); and when the prediction type is the intra prediction type, theintra prediction information is provided to the intra decoder (772). Theresidual information can be subject to inverse quantization and isprovided to the residue decoder (773).

The inter decoder (780) is configured to receive the inter predictioninformation, and generate inter prediction results based on the interprediction information.

The intra decoder (772) is configured to receive the intra predictioninformation, and generate prediction results based on the intraprediction information.

The residue decoder (773) is configured to perform inverse quantizationto extract de-quantized transform coefficients, and process thede-quantized transform coefficients to convert the residual from thefrequency domain to the spatial domain. The residue decoder (773) mayalso require certain control information (to include the QuantizerParameter QP), and that information may be provided by the entropydecoder (771) (datapath not depicted as this may be low volume controlinformation only).

The reconstruction module (774) is configured to combine, in the spatialdomain, the residual as output by the residue decoder (773) and theprediction results (as output by the inter or intra prediction modulesas the case may be) to form a reconstructed block, that may be part ofthe reconstructed picture, which in turn may be part of thereconstructed video. It is noted that other suitable operations, such asa deblocking operation and the like, can be performed to improve thevisual quality.

It is noted that the video encoders (303), (503) and (603), and thevideo decoders (310), (410) and (710) can be implemented using anysuitable technique. In an embodiment, the video encoders (303), (503)and (603), and the video decoders (310), (410) and (710) can beimplemented using one or more integrated circuits. In anotherembodiment, the video encoders (303), (503) and (503), and the videodecoders (310), (410) and (710) can be implemented using one or moreprocessors that execute software instructions.

FIG. 8 illustrates an example of block partitioning by using aQuad-tree-Binary-tree (QTBT) structure and the corresponding treerepresentation. A QTBT structure unifies the concepts of the coding unit(CU), prediction unit (PU), and transform unit (TU) and supports moreflexibility for CU partition shapes. In the QTBT block structure, a CUcan have either a square or rectangular shape. As shown in FIG. 8, a CTUis first partitioned by a quad-tree structure. The quad-tree leaf nodesare further partitioned by a binary tree structure. There are twosplitting types, symmetric horizontal splitting and symmetric verticalsplitting, in the binary tree splitting. The binary tree leaf nodes arecalled CUs, and that segmentation is used for prediction and transformprocessing without any further partitioning. This means that the CU, PUand TU have the same block size in the QTBT coding block structure. A CUsometimes has coding blocks (CBs) of different color components, e.g.,one CU contains one luma CB and two chroma CBs in the case of P and Bslices of the 4:2:0 chroma format and sometimes has a CB of a singlecomponent, e.g., one CU contains only one luma CB or just two chroma CBsin the case of I slices. The solid lines indicate quad-tree splittingand dotted lines indicate binary tree splitting. In each splitting(i.e., non-leaf) node of the binary tree, one flag is signaled toindicate which splitting type (i.e., horizontal or vertical) is used,where 0 indicates horizontal splitting and 1 indicates verticalsplitting. For the quad-tree splitting, there is no need to indicate thesplitting type since quad-tree splitting always splits a block bothhorizontally and vertically to produce 4 sub-blocks with an equal size.

In the above-described tree structure or other advanced tree structure,a block at a certain depth may be further split into several smallerblocks. All these blocks may be in inter-prediction mode and share thesame motion. It is inefficient to code these blocks with the relatedcoding technology if only one or two of the smaller blocks have non-zerocoefficients because some information, such as inter-prediction mode andmotion, is duplicately coded for these smaller blocks.

In an embodiment of the present disclosure, the CUs that belong to thesame parent block may be combined when the CUs share or are associatedwith the same inter-prediction information. The inter-predictioninformation can include the motion information of the CUs. For example,as shown in FIG. 8, the first CU (800), the second CU (810), and thethird CU (820) are partitioned from the same parent block (830). Thus,they may be combined as a single coding block for the purpose ofencoding and decoding if they share the same inter-predictioninformation, while the coefficients of each CU is coded/decodedseparately. As a result, coding blocks associated with the sameinter-prediction information are not duplicately coded/decoded andcoding/decoding efficiency is improved.

A new syntax element, such as a combined inter coding unit modeflag/indicator can be used to indicate whether all the child CUspartitioned from the same parent block share the same inter-predictioninformation. The combined inter coding unit mode flag may be signaled tothe decoder.

FIG. 9 shows an example of combining child CUs into a single block whenall the child CUs belong to the same parent block and share the sameinter-prediction information. A parent block 900 is partitioned intonine child CUs (910-918). When the combined inter coding unit mode flagis signaled to indicate that all the child CUs share the sameinter-prediction information, all the child CUs (910-918) may becombined into one single block 930. The single block 930 shares the sameinter-prediction information. As a result, motion information is onlycoded once, is signaled for one of the child CUs, and is shared amongall the child CUs (910-918). For example, only the motion information ofone of the child CUs (910) or the first child CU (in coding order) issignaled and this child CU may be coded in merge mode or in regularinter-prediction mode with motion vector difference signaled.

In an embodiment of the present disclosure, a splitting/partition typeof a parent block may be signaled to the decoder. The splitting type ofa parent block indicates how many child CUs are partitioned from theparent block and may include the partition structure of the parentblock. In an embodiment of the present disclosure, only when thesplitting type of the parent block indicates that the parent block ispartitioned into more than one child CU can the child CUs be combined.For example, the child CUs can be combined only when the splitting typeof parent block indicates that the parent block is partitioned into morethan N child CUs. Exemplary value of N may include, but is not limitedto 2, 3, or 4.

After the splitting type of a parent block is signaled, the combinedinter coding unit mode flag is signaled to indicate whether all thechild CUs that belong to the same parent block share the sameinter-prediction information. In this case, the combined inter codingunit mode flag may be signaled as 1, and all the child CUs may beinferred as non-intra block and no signaling on intra/inter mode isneeded. In another embodiment of the present disclosure, the child CUspartitioned from the parent block may have both intra and non-intracoded blocks, but all the inter-coded blocks share the same motion, andthe motion information is only coded once after the combined inter CUmode flag is signaled as 1. The combined inter CU mode flag may also besignaled as 0, which indicates that not all the child CUs that belong tothe same parent block share the same inter-prediction information. Whenall the child CUs except the last one share the same motion, the lastchild CU (in coding order) is determined to have different motioninformation. In this case, when signaling the motion information of thelast child CU, the merge candidates for the last child CU may beadjusted to exclude those candidates (e.g., the previously coded CUspartitioned from this parent block) that share the same motion of thepreviously coded CUs. As a result, the signaling cost can be reduced.

It is noted that the splitting type of a parent block is not limited tothe QTBT structure described above. Other splitting type examples of aparent block may be Multi-Type-Tree Structure, Asymmetric Coding Unitsin QTBT, Flexible Tree Structure, and Binary Tree With Shift. Thepresent method of combining child CUs that share the sameinter-predication information can be used in any splitting type/treestructure.

In an embodiment of the present disclosure, the combined inter CU modeflag is only signaled under certain conditions. The conditions include,but are not limited to: the block area size needs to be same as, orlarger than, or smaller than a given threshold. The threshold mayinclude, but is not limited to 32 samples, 64 samples, 128 samples, or256 samples. Similarly, the block width (and/or height) needs to be sameas, or larger than, or smaller than a given threshold. The threshold mayinclude, but is not limited to 4 samples, 8 samples, or 16 samples.

In an embodiment of the present disclosure, all the child CUs may not beallowed to be further split when all the child CUs partitioned from theparent block share the same predication information. Alternatively, inanother embodiment of the present disclosure, the child CUs may befurther split to N depth, exemplary value of N may include, but is notlimited to 1, 2, or 3. When N is 0, it means that all the child CUs arenot allowed to be further split. Furthermore, in one example, at mostonly one child CU has a non-zero coefficient. In another example, atmost only one child CU has a non-zero coefficient if the spitting typeof the parent block indicates that there are no more than three childCUs partitioned from the parent block. In another example, at most onlytwo child CUs have non-zero coefficients.

In an embodiment of the present disclosure, a coded block flag (CBF)root, which signals whether a CU has a non-zero coefficient, may bederived for the last coded child CU based on the constraints of thenumber of child CUs which have non-zero coefficients. Specifically,whether the last coded child CU contains a non-zero coefficient can bedetermined based on a number of the plurality of inter-coded blocks thatprecede the last coded block and contain no non-zero coefficients whenthe parent block is signaled to include at least one non-zerocoefficient. For example, if the first child CU is coded as skip, andthere are only two child CUs partitioned from the parent block, the CBFroot of the second child CU can be inferred as one. Thus, a CBF rootsignal for the last coded CU is not needed.

In another example, when there are three child CUs partitioned from theparent block, only one child CU has a non-zero coefficient, and one ofthe first two child CUs has a non-zero coefficient, the last coded childCU can be determined to not have non-zero coefficient. Thus, a CBF rootsignal for the last coded CU is not needed. As a result, signaling costcan be reduced.

FIG. 10 shows a flow chart outlining a process (1000) according to someembodiments of the disclosure. The process (1000) can be used in thereconstruction of a block coded in inter mode, so to generate aprediction block for the block under reconstruction. In variousembodiments, the process (1000) are executed by processing circuitry,such as the processing circuitry in the terminal devices (210), (220),(230) and (240), the processing circuitry that performs functions of thevideo encoder (303), the processing circuitry that performs functions ofthe video decoder (310), the processing circuitry that performsfunctions of the video decoder (410), the processing circuitry thatperforms functions of the motion compensation prediction module (453),the processing circuitry that performs functions of the video encoder(503), the processing circuitry that performs functions of the predictor(535), the processing circuitry that performs functions of the interencoder (630), the processing circuitry that performs functions of theinter decoder (780), and the like. In some embodiments, the process(1000) is implemented in software instructions, thus when the processingcircuitry executes the software instructions, the processing circuitryperforms the process (1000). The process starts at (S1001) and proceedsto (S1030).

At (S1010), a combined inter coding unit mode indicator is received.

At (S1020), inter-prediction information for one of a plurality ofblocks in a current picture is received and the inter-predictioninformation includes motion information of the one of the plurality ofblocks.

At (S1030), each of the plurality of blocks according to theinter-prediction information of the one of the plurality of blocks isreconstructed based on a determination that the combined inter codingunit indicator indicates that each of the plurality of blockspartitioned from a parent block is associated with the inter-predictioninformation of the one of the plurality of blocks. Then the processproceeds to (S1099) and terminates.

The techniques described above, can be implemented as computer softwareusing computer-readable instructions and physically stored in one ormore computer-readable media. For example, FIG. 11 shows a computersystem suitable for implementing certain embodiments of the disclosedsubject matter.

The computer software can be coded using any suitable machine code orcomputer language, that may be subject to assembly, compilation,linking, or like mechanisms to create code comprising instructions thatcan be executed directly, or through interpretation, micro-codeexecution, and the like, by one or more computer central processingunits (CPUs), Graphics Processing Units (GPUs), and the like.

The instructions can be executed on various types of computers orcomponents thereof, including, for example, personal computers, tabletcomputers, servers, smartphones, gaming devices, internet of thingsdevices, and the like.

The components shown in FIG. 11 for computer system are exemplary innature and are not intended to suggest any limitation as to the scope ofuse or functionality of the computer software implementing embodimentsof the present disclosure. Neither should the configuration ofcomponents be interpreted as having any dependency or requirementrelating to any one or combination of components illustrated in theexemplary embodiment of a computer system (1100).

Computer system (1100) may include certain human interface inputdevices. Such a human interface input device may be responsive to inputby one or more human users through, for example, tactile input (such as:keystrokes, swipes, data glove movements), audio input (such as: voice,clapping), visual input (such as: gestures), olfactory input (notdepicted). The human interface devices can also be used to capturecertain media not necessarily directly related to conscious input by ahuman, such as audio (such as: speech, music, ambient sound), images(such as: scanned images, photographic images obtain from a still imagecamera), video (such as two-dimensional video, three-dimensional videoincluding stereoscopic video).

Input human interface devices may include one or more of (only one ofeach depicted): keyboard (1101), mouse (1102), trackpad (1103), touchscreen (1110), data-glove (not shown), joystick (1105), microphone(1106), scanner (1107), camera (1108).

Computer system (1100) may also include certain human interface outputdevices. Such human interface output devices may be stimulating thesenses of one or more human users through, for example, tactile output,sound, light, and smell/taste. Such human interface output devices mayinclude tactile output devices (for example tactile feedback by thetouch-screen (1110), data-glove (not shown), or joystick (1105), butthere can also be tactile feedback devices that do not serve as inputdevices), audio output devices (such as: speakers (1109), headphones(not depicted)), visual output devices (such as screens (1110) toinclude CRT screens, LCD screens, plasma screens, OLED screens, eachwith or without touch-screen input capability, each with or withouttactile feedback capability—some of which may be capable to output twodimensional visual output or more than three dimensional output throughmeans such as stereographic output; virtual-reality glasses (notdepicted), holographic displays and smoke tanks (not depicted)), andprinters (not depicted).

Computer system (1100) can also include human accessible storage devicesand their associated media such as optical media including CD/DVD ROM/RW(1120) with CD/DVD or the like media (1121), thumb-drive (1122),removable hard drive or solid state drive (1123), legacy magnetic mediasuch as tape and floppy disc (not depicted), specialized ROM/ASIC/PLDbased devices such as security dongles (not depicted), and the like.

Those skilled in the art should also understand that term “computerreadable media” as used in connection with the presently disclosedsubject matter does not encompass transmission media, carrier waves, orother transitory signals.

Computer system (1100) can also include an interface to one or morecommunication networks. Networks can for example be wireless, wireline,optical. Networks can further be local, wide-area, metropolitan,vehicular and industrial, real-time, delay-tolerant, and so on. Examplesof networks include local area networks such as Ethernet, wireless LANs,cellular networks to include GSM, 3G, 4G, 5G, LTE and the like, TVwireline or wireless wide area digital networks to include cable TV,satellite TV, and terrestrial broadcast TV, vehicular and industrial toinclude CANBus, and so forth. Certain networks commonly require externalnetwork interface adapters that attached to certain general purpose dataports or peripheral buses (1149) (such as, for example USB ports of thecomputer system (1100)); others are commonly integrated into the core ofthe computer system (1100) by attachment to a system bus as describedbelow (for example Ethernet interface into a PC computer system orcellular network interface into a smartphone computer system). Using anyof these networks, computer system (1100) can communicate with otherentities. Such communication can be uni-directional, receive only (forexample, broadcast TV), uni-directional send-only (for example CANbus tocertain CANbus devices), or bi-directional, for example to othercomputer systems using local or wide area digital networks. Certainprotocols and protocol stacks can be used on each of those networks andnetwork interfaces as described above.

Aforementioned human interface devices, human-accessible storagedevices, and network interfaces can be attached to a core (1140) of thecomputer system (1100).

The core (1140) can include one or more Central Processing Units (CPU)(1141), Graphics Processing Units (GPU) (1142), specialized programmableprocessing units in the form of Field Programmable Gate Areas (FPGA)(1143), hardware accelerators for certain tasks (1144), and so forth.These devices, along with Read-only memory (ROM) (1145), Random-accessmemory (1146), internal mass storage such as internal non-useraccessible hard drives, SSDs, and the like (1147), may be connectedthrough a system bus (1148). In some computer systems, the system bus(1148) can be accessible in the form of one or more physical plugs toenable extensions by additional CPUs, GPU, and the like. The peripheraldevices can be attached either directly to the core's system bus (1148),or through a peripheral bus (1149). Architectures for a peripheral businclude PCI, USB, and the like.

CPUs (1141), GPUs (1142), FPGAs (1143), and accelerators (1144) canexecute certain instructions that, in combination, can make up theaforementioned computer code. That computer code can be stored in ROM(1145) or RAM (1146). Transitional data can be also be stored in RAM(1146), whereas permanent data can be stored for example, in theinternal mass storage (1147). Fast storage and retrieve to any of thememory devices can be enabled through the use of cache memory, that canbe closely associated with one or more CPU (1141), GPU (1142), massstorage (1147), ROM (1145), RAM (1146), and the like.

The computer readable media can have computer code thereon forperforming various computer-implemented operations. The media andcomputer code can be those specially designed and constructed for thepurposes of the present disclosure, or they can be of the kind wellknown and available to those having skill in the computer software arts.

As an example and not by way of limitation, the computer system havingarchitecture (1100), and specifically the core (1140) can providefunctionality as a result of processor(s) (including CPUs, GPUs, FPGA,accelerators, and the like) executing software embodied in one or moretangible, computer-readable media. Such computer-readable media can bemedia associated with user-accessible mass storage as introduced above,as well as certain storage of the core (1140) that are of non-transitorynature, such as core-internal mass storage (1147) or ROM (1145). Thesoftware implementing various embodiments of the present disclosure canbe stored in such devices and executed by core (1140). Acomputer-readable medium can include one or more memory devices orchips, according to particular needs. The software can cause the core(1140) and specifically the processors therein (including CPU, GPU,FPGA, and the like) to execute particular processes or particular partsof particular processes described herein, including defining datastructures stored in RAM (1146) and modifying such data structuresaccording to the processes defined by the software. In addition or as analternative, the computer system can provide functionality as a resultof logic hardwired or otherwise embodied in a circuit (for example:accelerator (1144)), which can operate in place of or together withsoftware to execute particular processes or particular parts ofparticular processes described herein. Reference to software canencompass logic, and vice versa, where appropriate. Reference to acomputer-readable media can encompass a circuit (such as an integratedcircuit (IC)) storing software for execution, a circuit embodying logicfor execution, or both, where appropriate. The present disclosureencompasses any suitable combination of hardware and software.

APPENDIX A: ACRONYMS

-   MV: Motion Vector-   HEVC: High Efficiency Video Coding-   SEI: Supplementary Enhancement Information-   VUI: Video Usability Information-   GOPs: Groups of Pictures-   Ms: Transform Units,-   PUs: Prediction Units-   CTUs: Coding Tree Units-   CTBs: Coding Tree Blocks-   PBs: Prediction Blocks-   HRD: Hypothetical Reference Decoder-   SNR: Signal Noise Ratio-   CPUs: Central Processing Units-   GPUs: Graphics Processing Units-   CRT: Cathode Ray Tube-   LCD: Liquid-Crystal Display-   OLED: Organic Light-Emitting Diode-   CD: Compact Disc-   DVD: Digital Video Disc-   ROM: Read-Only Memory-   RAM: Random Access Memory-   ASIC: Application-Specific Integrated Circuit-   PLD: Programmable Logic Device-   LAN: Local Area Network-   GSM: Global System for Mobile communications-   LTE: Long-Term Evolution-   CANBus: Controller Area Network Bus-   USB: Universal Serial Bus-   PCI: Peripheral Component Interconnect-   FPGA: Field Programmable Gate Areas-   SSD: solid-state drive-   IC: Integrated Circuit-   CU: Coding Unit

While this disclosure has described several exemplary embodiments, thereare alterations, permutations, and various substitute equivalents, whichfall within the scope of the disclosure. It will thus be appreciatedthat those skilled in the art will be able to devise numerous systemsand methods which, although not explicitly shown or described herein,embody the principles of the disclosure and are thus within the spiritand scope thereof.

What is claimed is:
 1. A method for video decoding in a decoder,comprising: receiving a combined inter coding unit mode indicator, thecombined inter coding unit mode indicator indicating whether each of aplurality of inter-coded blocks partitioned from a parent block shares amotion vector of one of the plurality of inter-coded blocks; in responseto a determination that the combined inter coding unit mode indicatorindicates that each of the plurality of inter-coded blocks partitionedfrom the parent block shares the motion vector of the one of theplurality of inter-coded blocks, receiving inter-prediction informationfor the one of the plurality of inter-coded blocks in a current picture,the inter-prediction information indicating the motion vector of the oneof the plurality of inter-coded blocks, and reconstructing each of theplurality of inter-coded blocks according to the inter-predictioninformation of the one of the plurality of inter-coded blocks; and inresponse to a determination that the combined inter coding unit modeindicator does not indicate that each of the plurality of inter-codedblocks partitioned from the parent block shares the motion vector of theone of the plurality of inter-coded blocks, receiving motion informationfor each of the plurality of inter-coded blocks except a last codedblock of the plurality of inter-coded blocks, respectively, the lastcoded block determined to have motion information different from thereceived motion information when each of the plurality of inter-codedblocks except the last coded block of the plurality of inter-codedblocks shares the motion vector of the one of the plurality ofinter-coded blocks.
 2. The method according to claim 1, wherein thecombined inter coding unit mode indicator is received after apartitioning type of the parent block is signaled, the partitioning typeof the parent block indicating that the parent block is partitioned intothe plurality of inter-coded blocks.
 3. The method according to claim 1,wherein merge candidates of the last coded block are updated to excludemerge candidates that result in a same motion as the plurality ofinter-coded blocks except the last coded block when each of theplurality of inter-coded blocks except the last coded block of theplurality of inter-coded blocks shares the motion vector of the one ofthe plurality of inter-coded blocks.
 4. The method according to claim 1,wherein the combined inter coding unit mode indicator is received onlywhen at least one of (i) a block area size of the parent block satisfiesa first condition and (ii) a block width of the parent block satisfies asecond condition.
 5. The method according to claim 1, wherein when thecombined inter coding unit mode indicator indicates that each of theplurality of inter-coded blocks partitioned from the parent block sharesthe motion vector of the one of the plurality of inter-coded blocks, theplurality of inter-coded blocks are not further partitioned.
 6. Themethod according to claim 1, further comprising: when the combined intercoding unit mode indicator indicates that each of the plurality ofinter-coded blocks partitioned from the parent block shares the motionvector of the one of the plurality of inter-coded blocks, receiving onlythe inter-prediction information of the one of the plurality ofinter-coded blocks.
 7. The method according to claim 1, wherein when thecombined inter coding unit mode indicator indicates that each of theplurality of inter-coded blocks partitioned from the parent block sharesthe motion vector of the one of the plurality of inter-coded blocks, atleast one of the plurality of inter-coded blocks contains a non-zerocoefficient.
 8. The method according to claim 1, wherein when thecombined inter coding unit mode indicator indicates that each of theplurality of inter-coded blocks partitioned from the parent block sharesthe motion vector of the one of the plurality of inter-coded blocks, atmost one of the plurality of inter-coded blocks contains a non-zerocoefficient.
 9. The method according to claim 1, wherein when thecombined inter coding unit mode indicator indicates that each of theplurality of inter-coded blocks partitioned from the parent block sharesthe motion vector of the one of the plurality of inter-coded blocks, atmost two of the plurality of inter-coded blocks contain non-zerocoefficients.
 10. The method according to claim 1, further comprising:when the combined inter coding unit mode indicator indicates that eachof the plurality of inter-coded blocks partitioned from the parent blockshares the motion vector of the one of the plurality of inter-codedblocks, determining whether a last coded block contains a non-zerocoefficient based on a number of the plurality of inter-coded blocksthat precede the last coded block and contain no non-zero coefficientswhen the parent block is signaled to include at least one non-zerocoefficient.
 11. The method according to claim 1, wherein when thecombined inter coding unit mode indicator indicates that each of theplurality of inter-coded blocks partitioned from the parent block sharesthe motion vector of the one of the plurality of inter-coded blocks, aprediction mode of each of the plurality of inter-coded blocks is notsignaled.
 12. The method according to claim 1, wherein the parent blockis partitioned into a plurality of child blocks, the child blocksincluding the plurality of inter-coded blocks and a plurality ofintra-coded blocks, and when the combined inter coding indicatorindicates that each of the plurality of inter-coded blocks partitionedfrom the parent block shares the motion vector of the one of theplurality of inter-coded blocks, motion information of the plurality ofinter-coded blocks is coded only once.
 13. An apparatus, comprising:processing circuitry configured to receive a combined inter coding unitmode indicator, the combined inter coding unit mode indicator indicatingwhether each of a plurality of inter-coded blocks partitioned from aparent block shares a motion vector of one of the plurality ofinter-coded blocks; in response to a determination that the combinedinter coding unit mode indicator indicates that each of the plurality ofinter-coded blocks partitioned from the parent block shares the motionvector of the one of the plurality of inter-coded blocks, receiveinter-prediction information for the one of the plurality of inter-codedblocks in a current picture, the inter-prediction information indicatingthe motion vector of the one of the plurality of inter-coded blocks, andreconstruct each of the plurality of inter-coded blocks according to theinter-prediction information of the one of the plurality of inter-codedblocks; and in response to a determination that the combined intercoding unit mode indicator does not indicate that each of the pluralityof inter-coded blocks partitioned from the parent block shares themotion vector of the one of the plurality of inter-coded blocks, receivemotion information for each of the plurality of inter-coded blocksexcept a last coded block of the plurality of inter-coded blocks,respectively, the last coded block determined to have motion informationdifferent from the received motion information when each of theplurality of inter-coded blocks except the last coded block of theplurality of inter-coded blocks shares the motion vector of the one ofthe plurality of inter-coded blocks.
 14. The apparatus according toclaim 13, wherein the combined inter coding unit mode indicator isreceived after a partitioning type of the parent block is signaled, thepartitioning type of the parent block indicating that the parent blockis partitioned into the plurality of inter-coded blocks.
 15. Theapparatus according to claim 13, wherein merge candidates of the lastcoded block are updated to exclude merge candidates that result in asame motion as the plurality of inter-coded blocks except the last codedblock when each of the plurality of inter-coded blocks except the lastcoded block of the plurality of inter-coded blocks shares the motionvector of the one of the plurality of inter-coded blocks.
 16. Theapparatus according to claim 13, wherein the combined inter coding unitmode indicator is received only when at least one of (i) a block areasize of the parent block satisfies a first condition and (ii) a blockwidth of the parent block satisfies a second condition.
 17. Theapparatus according to claim 13, wherein when the combined inter codingunit mode indicator indicates that each of the plurality of inter-codedblocks partitioned from the parent block shares the motion vector of theone of the plurality of inter-coded blocks, the plurality of inter-codedblocks are not further partitioned.
 18. The apparatus according to claim13, wherein when the combined inter coding unit mode indicator indicatesthat each of the plurality of inter-coded blocks partitioned from theparent block shares the motion vector of the one of the plurality ofinter-coded blocks, the processing circuitry is further configured toreceive only the inter-prediction information of the one of theplurality of inter-coded blocks.
 19. The apparatus according to claim13, wherein when the combined inter coding unit mode indicates that eachof the plurality of inter-coded blocks partitioned from the parent blockshares the motion vector of the one of the plurality of inter-codedblocks, at least one of the plurality of inter-coded blocks contains anon-zero coefficient.
 20. A non-transitory computer-readable mediumstoring instructions which when executed by a computer for videodecoding cause the computer to perform: receiving a combined intercoding unit mode indicator, the combined inter coding unit modeindicator indicating whether each of a plurality of inter-coded blockspartitioned from a parent block shares a motion vector of one of theplurality of inter-coded blocks; in response to a determination that thecombined inter coding unit mode indicator indicates that each of theplurality of inter-coded blocks partitioned from the parent block sharesthe motion vector of the one of the plurality of inter-coded blocks,receiving inter-prediction information for the one of the plurality ofinter-coded blocks in a current picture, the inter-predictioninformation indicating the motion vector of the one of the plurality ofinter-coded blocks, and reconstructing each of the plurality ofinter-coded blocks according to the inter-prediction information of theone of the plurality of inter-coded blocks; and in response to adetermination that the combined inter coding unit mode indicator doesnot indicate that each of the plurality of inter-coded blockspartitioned from the parent block shares the motion vector of the one ofthe plurality of inter-coded blocks, receiving motion information foreach of the plurality of inter-coded blocks except a last coded block ofthe plurality of inter-coded blocks, respectively, the last coded blockdetermined to have motion information different from the received motioninformation when each of the plurality of inter-coded blocks except thelast coded block of the plurality of inter-coded blocks shares themotion vector of the one of the plurality of inter-coded blocks.